Principle, advantages and disadvantages of differential pressure flowmeter

sales01@cxflowmeter.com

How about the flowmeter, differential pressure flow meter is one of the most widely used flowmeters at present. It has the characteristics of simple structure, wide application range, easy maintenance, and easy production of standard parts, so it is widely used in the petroleum and petrochemical industry.

1. Uniform tube flow measurement device (such as powerbar, brand of flowmeter agniuba, deltaba, wilba, hyperbaric, etc.)

1. Principle;Based on the pitot tube velocity measurement principle, the flow rate is calculated by measuring several velocity points on the straight line of the pipeline.

2, advantages: simple structure, low price, easy to install and dismantle, small pressure loss and other characteristics.The multi-point arrangement can be realized to measure the average velocity of large wind passage.

3. Disadvantages: the pressure extraction hole is adopted for pressure extraction, and the pressure extraction mouth is easy to be blocked, which requires high fluid cleanliness, large operation and maintenance, and is not suitable for air measurement of medium containing powder;Since it is multi-point measurement, backblowing can only blow through individual points, and it is difficult to blow through all the extraction holes.

2. Venturi type flow measurement device (such as single throat diameter, double throat diameter, multi-throat venturi flow meter)

1. The principle is that the throat of the venturi tube is used to accelerate the formation of low pressure, and the tail of the venturi tube is placed in the throat area of low pressure to promote the formation of lower low pressure in the throat of the venturi tube, so that a larger output differential pressure can be obtained at the same flow rate.

2. Advantages: it is more suitable for the measurement of gas flow rate with low flow rate in large pipelines.It's fast.

3. Disadvantages;Because it only measures a point velocity, the velocity distribution in the pipe has a great influence on it, so the accuracy is low.At present, there is a kind of three-venturi tube on the market. It installs another venturi tube in the double-venturi tube in an attempt to obtain a larger differential pressure. When the size is small, the effect of boundary layer will appear, which restricts the effect of accelerating and reducing pressure, and brings about the negative impact of complex structure and unstable coefficient.When measuring the dusty air flow, the dust can only enter and exit, which causes the pressure sensing pipe to be blocked, the pressure outlet is easy to be blocked, and the operation and maintenance amount is large, so it is not suitable for the medium containing powder.When the cross-sectional area of the duct is large and the straight section is not long enough, the output differential pressure is not linear and the repeatability is poor.If single point arrangement, it is not suitable to measure the air volume of large air duct.

Airfoil flow measurement device

1, the theoretical basis of its measurement is: in the pipe filled with fluid, fixed place a circulation area is less than the pipe sectional area of the throttle, the pipe flow through the throttle parts can cause local contraction, the shrinkage velocity increases, the static pressure is reduced, so the throttle will produce a certain pressure difference before and after.For a certain shape and size of the throttle, a certain pressure measurement position and before and after the straight tube section, a certain fluid parameters, the throttle before and after the differential pressure △p and flow q relationship conforms to Bernoulli equation.

2. Advantages: quick response;Multi-point measurement of average velocity of large duct.